Plenty Done in a Short Distance: The Tragedy of Alan Turing

A significant contributor in the Allied effort during World War II and one of the key figures in advancing modern computing, Alan Turing’s name is likely a familiar one. His name and various references to the “Turing Test” (or the “Imitation Game”) have been featured in science fiction media over the decades (including at least one biopic starring Benedict Cumberbatch. I haven’t seen it, but it’s got an 89% on Rotten Tomatoes, so I’ll assume it’s good).

Alan Turing was born June 23, 1912 in London, England to Julius Turing and Ethel Sara Stoney. He studied Mathematics at the University of Cambridge in the early 1930s, graduating in 1934. Turing published his paper “On Computable Numbers, with an Application to the Entscheidungsproblem” in the Proceedings of the London Mathematical Society journal in 1936.

The Entscheidungsproblem, German for “decision problem,” was a challenge to create an algorithm (a set of rules or instructions with problem-solving or operational steps) that accepted formal language input, a logical statement in that language, and answered if the statement expression was universally true or false for the language. So, the decision problem is a question of whether it is possible to programmatically determine if a program will run to completion or if any given statement is valid in that language (the program won’t terminate with an error in finite, calculable time). In his paper, Turing concluded that such an algorithm is impossible – a conclusion that had been independently reached by Alonzo Church in a paper published in the American Mathematical Society’s journal in 1935.

With a similar conclusion having been reached and published so recently before Turing’s submission, the London Mathematical Society was reluctant to publish Turing’s findings, however this decision was challenged by Max Newman, Turing’s mentor. Newman argued that Turing’s method of reaching the same conclusion was sufficiently different from Church’s, so the paper was published. Following the publication of his paper, Turing would move to Princeton University to study under Alonzo Church and achieve his Ph.D. from Princeton in 1938.

Turing returned to England in the summer of 1938 and subsequently joined the Government Code and Cypher School (GC&CS – this would later be known as the Government Communications Headquarters (GCHQ)) before the start of World War II in 1939. At the start of the war, Turing moved to Bletchley Park, where the GC&CS was headquartered during the war, and began working on a code breaking machine for the Allied war effort.

About 20 years before this, following the end of the first World War, a German engineer named Arthur Scherbius designed a device called an “Enigma Machine” that would later be used by German forces during the second World War to encrypt their communications. The enigma machine was similar in design to a typewriter, but it had another row of letters above the keyboard instead of typebars and a platen (the paper roller bit on a typewriter). When a key was pressed on the enigma machine, one of the letters above the keyboard would illuminate in a somewhat random progression with each keypress changing the letter assignment for each subsequent keypress and never equaling the key being pressed (e.g. the letter “s” would never be assigned the letter “s” in the encrypted message). The encrypted message was recorded as it was typed and then transmitted separately to be decrypted on the receiving end. It was these messages that Turing and his colleagues were attempting to crack.

Turing’s approach at decrypting these enigma messages was to compare a block of the encrypted message to a block of known plaintext believed to be in the message. Turing believed this approach, known as “cribbing,” could be automated or mechanized. The first machine that utilized this process (called a bombe) was named “Victory” and started work decrypting enigma messages on March 14, 1940.

Gordon Welchman, a mathematician and colleague of Turing’s at Bletchley Park, developed the “diagonal board,” which essentially helped to break down key-to-letter assignments. This new addition to the bombe helped to filter out false positives in the automated cribbing, which drastically reduced the time needed to decrypt a message. The first bombe to use the diagonal board, now called the Turing-Welchman Bombe, was called “Agnes” and began service in August of 1940.

The allied war effort relied heavily on the intelligence gained from these decrypted messages, so it was imperative that German forces remained unaware that the enigma machine had been cracked. Special liaisons were used to relay the intelligence without revealing sources. The codebreakers at Bletchley Park decoded nearly 40,000 messages per month by 1942 – a number that would eventually double before the war’s end. Turing would be recognized as an “Officer of the Most Excellent Order of the British Empire” for his accomplishments in code breaking, which may have shortened the war by two years.

We can only see a short distance ahead, but we can see plenty there that needs to be done.
Alan Turing

After the war, Turing was recruited by the National Physical Laboratory (NPL) to begin work on an electronic computer in 1945. He designed an Automatic Computing Engine (ACE) for the NPL, but it was deemed too difficult to engineer. In 1948, the first digital computer was built by the University of Manchester’s Royal Society Computing Machine Laboratory. Turing later accepted a position as the Deputy Director of the Computing Machine Laboratory in 1949 after the discouraging delays with the NPL’s computer. The NPL would eventually build a smaller, simpler machine than the one designed by Turing called the Pilot ACE; it ran its first program in May of 1950.

Turing theorized that the human brain was essentially an organic computing machine and pioneered the idea of artificial intelligence theory. He believed that the brain was essentially an unorganized machine that became “a universal machine or something like it” only after training and experience. In 1950, he proposed the “imitation game.”

The imitation game, or the Turing Test as it is now called, involves a remote interviewer receiving text responses to questions asked. The interrogator must then determine, based on the answers given, if the responses are being given by a human interviewee or a computer. If the computer is able to “trick” the interviewer into believing that the responses are being given by a human, then the computer has demonstrated its ability to think and reason. Turing predicted computers would be able to pass the Turing Test 70% of the time by the year 2000. In the year 2021, we have yet to match his prediction, but the Turing Test remains a popular staple in cyberpunk and sci-fi pop culture.

A computer would deserve to be called intelligent if it could deceive a human into believing that it was human.
Alan Turing

While working at Bletchley Park in 1941, Turing proposed marriage to Joan Clarke, a colleague of his. This engagement, however, was short lived as Turing confided in Joan that he was homosexual.

In 1952, Turing met and began a relationship with a man named Arnold Murray. On January 23, 1952, Turing had the misfortune of being burgled by one of Murray’s acquaintances. During the burglary investigation, it was disclosed that Turing and Murray were in a homosexual relationship – which was a criminal offense at this time. In March of that year, Turing was convicted of gross indecency and sentenced to undergo a 12-month hormonal procedure to suppress his homosexual urges (this punishment has been referred to as a chemical castration). Turing’s security clearance was revoked following this conviction and he was prohibited from being able to work for the GCHQ again as a result.

I want a permanent relationship and I might feel inclined to reject anything which of its nature could not be permanent.
Alan Turing

The hormonal treatment Turing was subjected to was a forced prescription of stilboestrol (a synthetic estrogen). This procedure was less a chemical castration and closer to the feminizing medical procedure a transgender individual may undergo, so the changes Turing experienced were not limited to impotence or suppressed homosexual urges. In a letter prior to his sentencing, Turing wrote of the pending treatment, “No doubt I shall emerge from it all a different man, but quite who I’ve not found out.” In another letter regarding his punishment, Turing wrote, “I have had a dream indicating rather clearly that I am on the way to being hetero, though I don’t accept it with much enthusiasm either awake or in the dreams.”

In 1954, a year following the completion of his prescribed-by-law punishment, Turing died of cyanide poisoning in what was ruled a suicide. Thirteen years following Turing’s death, homosexuality in the UK was decriminalized with the passage of the “Sexual Offences Act” of 1967. Turing was posthumously pardoned by Queen Elizabeth in 2013, nearly sixty years after he had passed.

Turing believes machines think
Turing lies with men
Therefore machines do not think
Alan Turing

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